Cooling system included in a battery charger for an electric vehicle

Abstract: [CONSTITUTION] A battery charger (28) for an electric vehicle comprises a built-in heatsink (162) provided with an air passage (163), and a built-in battery charger cooling fan (71) for producing an air current through the air passage (163) of the heatsink (162) to cool the heatsink (162). [EFFECT] The heatsink need not be provided with fins and hence the battery charger can be formed in a comparatively small size.

Description: DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to improvements in a cooling system for cooling a battery charger for an electric vehicle. Prior Art The applicant of the present patent application proposed a battery charger for an electric vehicle previously in Japanese Patent Laid-open (Kokai) No. 5-83863, which will hereinafter be referred to as a cited reference. As shown in Fig. 5 of the cited reference, heat generated by a choke coil 48 and an FET 49 is absorbed by a heatsink 43, and the heatsink 43 is cooled with air blown by an exhaust fan 45 to suppress the rise of the temperatures of the choke coil 48 and the FET 49. Problem to be Solved by the Invention As shown in Fig. 5 of the cited reference, the heatsink 43 is provided with fins having a comparatively large height. Therefore, a battery charger 40 shown in Fig. 4 of the cited reference has a comparatively large height and a comparatively large size. When the electric vehicle is a motorcycle, only a limited space is available for mounting equipment and the battery charger 40 must be formed in a comparatively small size. Accordingly, it is an object of the present invention to provide battery charger having a comparatively small size to be mounted on an electric vehicle. Means for Solving the Problem With the foregoing object in view, the present invention provides a cooling system included in a battery charger, comprising a heatsink provided with an air passage, and a battery charger cooling fan for producing an air current through the air passage of the heatsink to cool the heatsink. The heatsink is disposed with one end thereof contiguous with an air inlet formed in a battery charger case, and the battery charger cooling fan is disposed near the other end of the heatsink, or the heatsink is disposed with its longer side extended along the direction of width of the body of the electric vehicle, and FETs (field-effect transistors) are arranged in contact with the outer surface of the heatsink. Air discharged by the battery charger cooling fan may be discharged outside through a discharge hose connected to the battery charger case. The discharge hose is extended longitudinally of the body of the electric vehicle and is concealed from view by a side cover. Function Since the heatsink has a hollow construction and need not be provided with fins, the battery charger including the cooling system can be formed in a compact construction. Air flows through the air inlet, the air passage of the heatsink and the battery charger cooling fan in that order. Heat generated by the FETs is absorbed and dissipated by the heatsink to cool the FETs forcibly. Description of the Preferred Embodiments A cooling system in a preferred embodiment according to the present invention will be described hereinafter with reference to the accompanying drawings. Fig. 1 is a side view of an electric vehicle incorporating a battery unit cooling system of the present invention. An electric vehicle 1, which is what is called an electric motorcycle, comprises: a chassis frame 2 comprising a main frame 3, a head pipe 4 attached to the front end of the main frame 3, and a rear frame 5 extending obliquely upward from the rear end of the main frame 3; a front fork 7 supported on the head pipe 4; a front wheel 8 supported on the lower end of the front fork 7; a handlebar 9 attached to the upper end of the front fork 7; a battery case 10 suspended from the main frame 3; a swing power unit 14 including a driving motor 15 and pivotally joined at its front end to the rear end of the main frame 3 with a pivot shaft 13; a storage box 16 mounted on the rear frame 5; a seat 17 mounted on the rear frame 5; a rear shock absorber 18 having an upper end pivotally joined to the rear frame 5 and a lower end pivotally joined to the rear end of the swing power unit 14; and a rear wheel 21 supported on a rear axle 19 supported on the rear end of the swing power unit 14. Electric parts including a battery charger are arranged along the rear frame 5. The chassis frame 2 is covered entirely with a cowling and fenders, which will be described later. A seat locking mechanism serving also as a locking mechanism for locking a lid covering the mouth of a plug container is disposed behind the seat 17, which will be described later. In Fig. 1, indicated at 22 is a side stand, at 23 is a roller, at 14a is a recess for receiving the roller 23 therein, and at 24 is a license plate holder. Fig. 2 is a plan view of the chassis frame of the electric vehicle incorporating the battery unit cooling system of the present invention. The rear frame 5 has a substantially oval shape in a plan view. A down regulator 27, a charging controller 28 for controlling battery charging operation, a motor controller 29 for controlling the driving motor and the associated parts for traveling, a battery cooling fan 30, and a fuse box 31 are arranged in that order on the rear frame 5 from the rear side toward the front side. Electric components are connected to a wiring harness 32. The main frame 3 is a hollow pipe capable of serving as a main duct. One end of the main frame 3 is connected to a discharge duct 33 connected to the battery cooling fan 30. The construction of the main frame 3 serving also as a main duct will be described later. In this embodiment, six battery units 35 are held on the main frame 3; three battery units 35 are arranged longitudinally on the right-hand side of the main frame 3 and three battery units 35 are arranged longitudinally on the left-hand side of the main frame 3. The battery units 35 are held in place with a battery fastening bands 36. Fig. 3 is a cross sectional view of the chassis frame taken in the substantially middle portion of the chassis frame. The bottom plate 38 of the battery case 10 is disposed under the main frame 3, the battery units 35 are mounted on the bottom plate 38. Each battery unit 35 has an air inlet 35a connected to a branch duct 40 branching from the main frame 3. The bottom plate 38 is formed by bending a corrugated plate and has a comparatively high rigidity. The lower ends of the battery fastening bands 36 are joined to knuckles 39 formed on the right and left side of the bottom plate 38. Fig. 4 is an exploded perspective view of the chassis frame, the battery case and the components of the electric vehicle 1. A bridge bracket 41, a cross pipe 43 provided with a bracket 42 to which the upper end of the rear shock absorber 18 is joined pivotally, and a cross panel 45 provided with holes 44 for receiving screws for fastening the battery cooling fan are extended across and attache to the oval rear frame 5. The cross panel 45 is extended between brackets 12 for supporting the pivot shaft 13. Indicated at 46 and 47 are lugs for supporting the charging controller 28 and the motor controller 29. Substantially triangular brackets 49, 50 and 51 are suspended from the main frame 3, and the lower sides of the brackets 49, 50 and 51 are joined to the bottom plate 38. A long hinge pin 52 is inserted in knuckles 39 formed on each side of the bottom plate 38 and the knuckles formed at the lower ends of the battery fastening bands 36 to join the battery fastening bands 36 pivotally to the bottom plate 38. Lower side covers 54 are attached to the opposite sides of the battery case 10, and a front cover 55 is attached to the front end of the battery case 10. In Fig. 4, indicated at 56 is a main switch including an ignition key switch, at 57 are battery support plates, and at 58 and 59 are cushion members for preventing the lateral dislocation of the battery units 35. Fig. 5 is an exploded perspective view of a portion of the electric vehicle 1 around the controllers and the rear fender. A front controller support plate 61 is fastened to the lugs 46 (Fig. 4) with bolts, and a rear controller support plate 62 is fastened to the lugs 47 (Fig. 4) with bolts. The front controller support plate 61 is provided on its upper surface with a bracket 63 to which the battery cooling fan is attached. The front end of the charging controller 28 is fastened to the front controller support plate 61 with bolts 64. The front controller support plate 61 is provided with legs 61a at its opposite ends, and the motor controller 29 is fastened to the extremities of the legs 61a with bolts 65. The rear end of the charging controller 28 is fastened to the rear controller support plate 62 with bolts 66. The rear controller support plate 62 is provided with legs 62a at its opposite ends, and the rear end of a rear fender 69 is fastened to the legs 62a with bolts 67. The rear fender 69 extends over a rear wheel 21, not shown in Fig. 5, and serves also as a box for containing the charging controller 28 and the motor controller 29 and the associated parts. The internal components of the charging controller 28 generate heat during battery charging operation. Therefore, the charging controller 28 must be cooled by forced cooling. The charging controller 28 is provided with a charger cooling fan 71 and air inlet slots 72 are formed in the side wall of the charging controller 28 for forced cooling. A charging cable 73 provided with a plug 74 is stored in a charging cable box 76 formed of a resin by blow molding and provided with lugs 76a and 76b fastened to the chassis frame 2. Heat generated within the battery charger is discharged through a discharge hose 77 shown in the lower left-hand corner of Fig. 5. A rear mud guard 78 is attached to a bracket 79. Fig. 6 is a side view of the electric vehicle equipped with fenders and covers, Fig. 7 is an exploded perspective view of fenders and covers for covering the front portion of the chassis frame, and Fig. 8 is an exploded perspective view of fenders and covers covering the rear portion of the chassis frame. Shown in Fig. 7 are a front fender 80, a front inner upper cover 81, a front upper cover 82 joined to the upper end of the front fender 80, a front mud guard 83 joined to the lower end of the front fender 80, a handlebar cover 84, a front inner upper cover 85, a step board 86, and side floors 87. These covering members are assembled so as to cover the main frame 3 and the head pipe 4 as shown in Fig. 6. Referring to Fig. 8, the storage box 16 is surrounded by a main cover 90 and a central cover 91. Shown in Fig. 8 are a fuse box lid 92 put on the center cover 91 to close a fuse box so as to be removed from the center cover 91 when changing fuses, a first lid 93 and a second lid 94 covering a charging cable box, a rack 95, floor side covers 96 suspended from the step board 86 so as to cover the lower side openings of the battery case 10, and side covers 97 joined to the rear part of the lower edge of the main cover 90. These covering members are assembled so as to cover the main frame 3 and the rear frame 5 as shown in Fig. 6. Parts indicated by broken lines in Fig. 6 are those previously described with reference to Fig. 1 and hence the description thereof will be omitted. Fig. 9 is an enlarged side view of the components of a seat locking mechanism serving also as a lid locking mechanism for locking a lid covering the charging cable box arranged behind the seat of the electric vehicle incorporating the battery cooling system of the present invention. A bent locking bar (or a bent locking pipe) 101 is attached to the rear part of the lower surface of the seat 17 covering the upper open end of the storage box 16, and a seat switch 102 is disposed under the locking bar 101 and is attached to a switch support plate 103 fastened to the bridge bracket 41 with bolts. The switch support plate 103 will be described later in detail. The cable box is covered with a first lid 93 and a second lid 94. When taking out the charging cable 73 (Fig. 1) from the cable box, first the seat 17 is raised, the first lid 93 is opened, and then the second lid 94 is opened. The plug connected to the charging cable 73 is held by a plug holder 105. A locking lever 107 is connected to a key cylinder 106. When the key cylinder 106 is turned so as to turn the locking lever 107 upward, the seat 17 is released. Fig. 10 is a view taken along the arrow 10 in Fig. 9. Referring to Fig. 10, the switch support plate 103 is provided with a guide groove 108 for guiding the locking bar 101 in its upper portion, and two slots 109 and 110 having the shape of an arc of a circle formed respectively near the opposite ends of its lower portion. The seat switch 102 is fastened to a small bracket 112 with a bolt 111, and the small bracket 112 is welded to the front surface of the switch support plate 103 so that the seat switch 102 is disposed in the center of the lower portion of the switch support plate 103. A first swing plate 114, which is turned downward to actuate the seat switch 102 when the locking bar 101 is lowered, is supported pivotally on the switch support plate 103. A second swing plate 116 is supported pivotally on the switch support plate 103. The first swing plate 114 is biased counterclockwise by a spring 117, and the second swing plate is biased clockwise by the spring 117. When the passenger leaves the seat 17, the first swing plate 114 is turned slightly counterclockwise from the position shown in Fig. 10 by the spring 117, as far as its arm 118 comes into contact with a cam 119 formed on the second swing plate 116. Since the second swing plate 116 is stationary, the first swing plate 114 is unable to turn further counterclockwise and, consequently, the locking bar 101 is restrained from further upward movement by the first swing plate 114 and hence the seat 17 is locked in place and cannot be turned upward. The state shown in Fig. 10 is established and first swing plate 114 depresses the seat switch 102 when the passenger sits on the seat 17. The first swing plate 114 is turned slightly counterclockwise from the position shown in Fig. 10 by the spring 117 and is separated from the seat switch 102 when the passenger is not seated on the seat 17. Thus, it is possible to detect electrically whether or not the passenger is seated on the seat 17, while the seat 17 is locked in place. A procedure for raising the seat 17 will be described hereinafter. The key cylinder 106 (Fig. 9) is turned to turn the locking lever 107 upward. Consequently, the second swing plate 116 (Fig. 10) is turned counterclockwise and the cam 119 of the second swing plate 116 moves below the arm 118 of the first swing plate 114 to release the arm 118. Then, the first swing plate 114 is turned counterclockwise through a large angle by the spring 117 to enable the locking bar 101 to move upward, so that the seat 17 can be raised by hand. Fig. 11 is a bottom view of a battery charger relating with the present invention. A battery charger (charging controller) 28 comprises a battery charger case 161 provided with air inlet slots 72, built-in electric and electronic parts including a choke coil 171, a transformer 172 and capacitors 173, a built-in printed wiring board, a built-in heatsink 162 provided with an air passage 163 formed in it portion near a charging cable 73, FETs (field-effect transistors) 164 arranged along the heatsink 162, and a battery charger cooling fan 71 disposed on the longitudinal axis of the heatsink 162. The air inlet slots 72 are formed on the longitudinal axis of the heatsink 162. The heatsink 162 is a heat radiating part for quickly absorbing and dissipating the heat generated by a transistor, an IC chip or an electric part, such as a resistor. The heatsink 162 is formed of a material having a high heat-conductivity, such as aluminum. Indicated at 165 are mounting lugs and at 166 is an air outlet. Fig. 12 is a view taken along the arrow 12 in Fig. 11. The air inlet slots 72 are formed in one side wall of the battery charger case 161 to suck fresh air therethrough into the battery charger case 161. Fig. 13 is a view taken along the arrow 13 in Fig. 11. The heatsink 162 and the battery charger cooling fan 71 are arranged in a series arrangement within the battery charger case 161. Fig. 14 is a view taken along the arrow 14 in Fig. 11. A connector support plate 168 projects from the end wall of the battery charger case at a position near plugs 167. The operation of the battery charger shown in Figs. 11 to 14 will be described hereinafter. Referring to Fig. 11, when the battery charger cooling fan 71 is started, a negative pressure is produced within the battery charger case 161 and, consequently, fresh air is sucked through the air inlet slots 72 into the battery charger case 161. The fresh air absorbs heat from the heatsink 162 and becomes hot air and the hot air is discharged through the air outlet 166. As shown in Fig. 13, the heatsink 162 has a sufficiently large size and a large heat capacity, and is capable of absorbing heat from the FETs 164 to suppress the rise of the temperatures of the FETs 164. Since the FETs 164 is able to exhibit their ability at temperatures below a fixed temperature, it is important to cool the FETs 164 effectively. The heatsink 162 is not provided with any fins and is formed in a cylindrical shape, so that the battery charger 28 provided with the heatsink 162 has a comparatively small height. Referring to Fig. 14, the battery charger is characterized by the connector support plate 168 projecting from one end wall thereof. As shown in Fig. 12, the battery charger 28 has a large, flat upper surface 28a. The battery charger 28 is set in a temporary position as shown in Figs. 13 and 14, in which the upper surface 28a faces down, before the same is mounted on the electric vehicle 1. The temporary position of the battery charger 28 shown in Figs. 13 and 14 is inverse to a working position in which the battery charger 28 is mounted on the electric vehicle 1. The battery charger 28 is set in the temporary position and a connector, not shown, is connected to the plugs 167. The connector is supported securely by the connector support plate 168 so that an excessive force may not be exerted on the connector. Fig. 15 is a plan view of the rear portion of the electric vehicle provided with the battery charger relating with the present invention. The battery charger 28 is disposed above the rear fender 68, and the discharge hose 77 is connected to the air outlet 66 of the battery charger 28 so as to extend forward and to project obliquely downward from the side cover 97 as shown in Fig. 17. Even if the interior of the discharge hose 77 is splashed and wetted with water when, for example, the electric vehicle 1 is washed, water drips from the discharge hose 77 by gravity because the discharge hose 77 extends obliquely downward from the air outlet 66. Fig. 16 is a view taken along the line 16-16. The battery charger 28 is fastened at its rear end with bolts 66 to the rear controller support plate 62 fastened to the rear frame 5 with bolts. The discharge hose 77 is concealed from view by the side cover 97. Fig. 17 is a side view of the rear portion of the electric vehicle provided with the battery charger relating with the present invention. The main cover 90 is provided with an inclined projection 169 for deflecting air discharged forward through the discharge hose 77 downward. Therefore, the hot discharged air flows downward as indicated by the blank arrow. The side cover 97 may be provided with a discharge slit, and the inclined projection 169 and the discharge hose 77 may be omitted. The heatsink 162 may be provided with a plurality of air passages 163 corresponding to the air inlet slots 72. Effect of the Invention As is apparent from the foregoing description, according to the present invention, the battery charger cooling system included in the battery charger comprises the heatsink provided with an air passage, and a battery charger cooling fan for producing an air current through the air passage of the heatsink to cool the heatsink. Therefore, the heatsink need not be provided with fins and the battery charger can be formed in a compact construction. Since the heatsink is disposed with its one end contiguous with the air inlet slots formed in the battery charger case, and the battery charger cooling fan is disposed near the other end of the heatsink, fresh air is able to flow smoothly through the heatsink to cool the heatsink effectively. When the battery charger cooling system is disposed on the electric vehicle with the longer side of the heatsink extended along the direction of width of the body of the electric vehicle, the air inlet slots can be formed in the side surface of the body of the electric vehicle, which facilitates the design of the covers of the electric vehicle. Since the battery charger cooling fan discharges air through the discharge hose connected to the battery charger case, the position where the air is discharged from the electric vehicle can optionally be determined. Since the FETs (field-effect transistors) are arranged in contact with the outer surface of the heatsink, the FETs can forcibly be cooled to ensure the satisfactory performance of the FETs. Since the discharge hose is extended longitudinally of the body of the electric vehicle and is concealed from view by the side cover, the appearance of the body of the electric vehicle is not spoiled by the discharge hose. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side view of an electric vehicle incorporating a battery charger cooling system in accordance with the present invention. Fig. 2 is a plan view of a chassis frame and the associated parts included in the electric vehicle of Fig. 1. Fig. 3 is a cross-sectional view of the body of the electric vehicle of Fig. 1. Fig. 4 is an exploded perspective view of a chassis frame, a battery case and the associated parts included in the electric vehicle of Fig. 1. Fig. 5 is an exploded perspective view of controllers, a rear fender and other parts included in the electric vehicle of Fig. 1. Fig. 6 is a side view of the electric vehicle of Fig. 1 as equipped with fenders and covers. Fig. 7 is an exploded perspective view of fenders and covers for covering the front portion of the electric vehicle of Fig. 1. Fig. 8 is an exploded perspective view of fenders and covers for covering the rear portion of the electric vehicle of Fig. 1. Fig. 9 is an enlarged view of the components of the electric vehicle of Fig. 1, arranged behind the seat (a locking mechanism for locking the seat and a lid covering a plug container). Fig. 10 is a view taken along the arrow 10 in Fig. 9. Fig. 11 is a bottom view of a battery charger relating with the present invention. Fig. 12 is a view taken along the arrow 12 in Fig. 11. Fig. 13 is a view taken along the arrow 13 in Fig. 11. Fig. 14 is a view taken along the arrow 14 in Fig. 11. Fig. 15 is a plan view of the rear portion of the electric vehicle provided with the battery charger relating with the present invention. Fig. 16 is a view taken along the line 16-16 in Fig. 15. Fig. 17 is a side view of the rear portion of the electric vehicle provided with the battery charger relating with the present invention. DESCRIPTION OF REFERENCE CHARACTERS 1. Electric vehicle 28. Battery charger (Charging controller) 28a. Upper surface 71. Battery charger cooling fan 72. Air inlet slot 77. Discharge hose 161. Battery charger case 162. Heatsink 163. Air passage 164. FET 166. Air outlet 169. Inclined projection

Claims: A cooling system included in a battery charger (28) mounted on an electric vehicle (1), said cooling system comprising: a heatsink (162) of hollow construction to provide an air passage (163); and a battery charger cooling fan (71) for producing an air current through the air passage (163) of the heatsink (162) to cool the heatsink (162). A cooling system included in a battery charger (28) mounted on an electric vehicle (1) according to claim 1, wherein the heatsink (162) is disposed with one end thereof contiguous with an air inlet (72) formed in a battery charger case (161), and the battery charger cooling fan (71) is disposed near the other end of the heatsink (162). A cooling system included in a battery charge (28) mounted on an electric vehicle (1) according to claim 1, wherein the heatsink (162) is disposed with its longer side extended along the direction of width of the body of the electric vehicle (1). A cooling system included in a battery charger (28) mounted on an electric vehicle (1) according to claim 2, wherein air discharged from the battery charger case (161) by the battery charger cooling fan (71) is discharged outside through a discharge hose (77) connected to the battery charger case (161). A cooling system included in a battery charger (28) mounted on an electric vehicle (1) according to claim 3, wherein FETs (field-effect transistors) (164) are arranged in contact with the outer surface of the heatsink (162). A cooling system included in a battery charger (28) mounted on an electric vehicle (1) according to claim 4, wherein the discharge hose (77) is extended longitudinally of the body of the electric vehicle (1) and is concealed from view by a side cover (97).

Inventors: KAWAGUCHI KENJI, OGAWA MASAO, SAKO HIROYUKI, TORIYAMA MASAYUKI, KAWAGUCHI, KENJI, OGAWA, MASAO, SAKO, HIROYUKI, TORIYAMA, MASAYUKI, KAWAGUCHI, KENJI, C/O K.K. HONDA GIJUTSU KENKYUSHO, OGAWA, MASAO, C/O K.K. HONDA GIJUTSU KENKYUSHO, SAKO, HIROYUKI, C/O K.K. HONDA GIJUTSU KENKYUSHO, TORIYAMA, MASAYUKI, C/O KK HONDA GIJUTSU KENKYUSHO
Applicants: HONDA MOTOR CO LTD, HONDA GIKEN KOGYO KABUSHIKI KAISHA
Application year: 1994
Main classification: H02J7
IPC codes: B62J9, B60K1, H02J7, B60R16